Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 224Get this manual
GEAR HOUSING
Filling Gear Housing with Lubricant
IMPORTANT: DO NOT use automotive lubricant in gear housingUse only Quicksilver Gear Lube1Remove any old gasket material from "OIL" and "OIL LEVEL" plugs and from around plug openings of gear housing2Install new gaskets on "OIL" and "OIL LEVEL" plugsIMPORTANT: Never add lubricant to gear housing without first removing "OIL LEVEL" (vent) plug, as trapped air will prevent housing from being filledFill gear housing only when outboard is in operating position3With outboard in operating position, insert lubricant tube into "OIL" (fill) hole4Fill gear housing with lubricant, until excess starts to flow from "OIL LEVEL" (vent) hole (approximately 6.5 fl oz[195 mL] of Quicksilver Gear Lube)5Install "OIL LEVEL" (vent) plug6Remove lubricant tube and install "OIL" (fill) plug56456 56387